animals Article Does Traditional Feeding of Outdoor Guard Dogs Provide a Food Resource for Wild Mammals and Birds? Róza˙ Andrzejczak 1,2, Łukasz Dylewski 3 , Leszek Jerzak 2 , Branislav Pet’ko 1,4 and Łukasz Myczko 1,* 1 Department of Zoology, Pozna´nUniversity of Life Sciences, Wojska Polskiego 71 C, 60-625 Pozna´n,Poland; [email protected] (R.A.); [email protected] (B.P.) 2 Institute of Biological Scienes, University of Zielona Góra, 65-516 Zielona Góra, Poland; [email protected] 3 Institute of Dendrology, Polish Academy of Sciences, Parkowa 5, 62-035 Kórnik, Poland; [email protected] 4 University of Veterinary Medicine in Kosice, Komenského 68/73, 041 81 Košice, Slovakia * Correspondence: [email protected] Simple Summary: Access to food is crucial in the life of birds, and affects reproduction, survival and, consequently, population size. We investigated how traditional care of dogs affected rural birds and other animal populations. Using camera traps, it was found that the food fed to dogs was also taken by seven species of birds and at least three species of mammals. The most numerous species taking dog food was the house sparrow, Passer domesticus, which is declining in Europe. In the case of this species, females were more likely than males to use food provided for dogs, with a clear preference for food prepared in the human kitchen. We conclude that the food provided to domestic pets can be an important component of the diet of wild birds and mammals living close to humans. Abstract: Access to food is crucial in the life of birds and affects reproduction, survival and, conse- quently, population size. In the case of bird species inhabiting villages, poorer food conditions now exist, mainly because of changes in the lifestyle of rural residents and a reduction in the number of Citation: Andrzejczak, R.; Dylewski, farm animals traditionally housed in backyards. Recent changes have also affected dog populations Ł.; Jerzak, L.; Pet’ko, B.; Myczko, Ł. in villages, and the majority of them are no longer kept outside as guard dogs, but rather inside Does Traditional Feeding of Outdoor houses as pets. We investigated how traditional care of dogs impacted rural birds and other animal Guard Dogs Provide a Food Resource for Wild Mammals and Birds? Animals populations. The study was carried out at the end of winter and early spring in 29 farmsteads in 2021, 11, 1198. https://doi.org/ western Poland. Using camera traps, it was found that the food fed to dogs was also taken by seven 10.3390/ani11051198 species of birds and at least three species of mammals. The most numerous species taking dog food was the house sparrow, Passer domesticus, which is declining in Europe. In the case of this species, Received: 19 March 2021 females were more likely than males to use food given to dogs, with a clear preference for food Accepted: 19 April 2021 prepared in the human kitchen. We conclude that the food provided to domestic pets can be an Published: 22 April 2021 important component of the diet of wild birds and mammals living close to humans. Publisher’s Note: MDPI stays neutral Keywords: traditional food sources; farmland; pets; villages with regard to jurisdictional claims in published maps and institutional affil- iations. 1. Introduction Birds in farmland are declining across Europe, and one of the main reasons is de- creasing food resources resulting from the intensification of agriculture [1–3]. However, Copyright: © 2021 by the authors. in Central Europe, the population size of birds in farmland is generally higher due to Licensee MDPI, Basel, Switzerland. less-intensive agriculture [3,4], but also from the presence of refugia for many species in This article is an open access article agricultural holdings, both in the breeding season [5], and throughout the year [6]. To distributed under the terms and date, research has focused on the roles of plant food sources; weeds on the outskirts of conditions of the Creative Commons the village, and the remains of grain provided for poultry have been stressed [7]. Rural Attribution (CC BY) license (https:// backyards were identified as being particularly important at the end of winter [8], when the creativecommons.org/licenses/by/ 4.0/). availability of natural food sources is very limited, primarily as a result of the consumption Animals 2021, 11, 1198. https://doi.org/10.3390/ani11051198 https://www.mdpi.com/journal/animals Animals 2021, 11, 1198 2 of 8 of the best food sources [7]. The end of winter and the beginning of spring are the periods when birds replenish their energy resources which are necessary to start reproduction [9]. Therefore, accessing food during this period should involve the use of various available food resources. For example, feeding birds in gardens and yards is very common in villages and benefits many bird species [10]. But wild birds not only use food sources provided intentionally by humans, but also those provided unintentionally such as leftover feed provided to farm animals and waste food [7,10]. One example of the latter is food provided by farmers and owners to farm guard dogs [11]. The pattern of feeding dogs in villages has changed a lot recently and instead of food from the owner’s kitchen, more are fed with commercial food [12,13]. Moreover, due to sociological changes in villages [5,14], dogs are more often now typical pets, living in houses, rather than traditional guard animals [11]. Pet food is changing to have a greater proportion of plant ingredients, with a potentially visible impact on the environment [15]. However, Okin [15] did not discuss the link be- tween dog food and wild animals. Obviously, birds foraging in farmyards will also try to use food provided for dogs. Therefore, the main aim of the current study was to describe the number of wild species of birds and mammals accessing food provided for dogs. In order to estimate the extent of this phenomenon and identify which species of birds and mammals were involved, our study took place in the critical period at the end of winter and in early spring. To avoid problems with species identification and the potential impact on wild animals (e.g., their behaviour, especially vigilance etc.) we decided to conduct the study in a non-invasive way using camera traps which have become popular in the study of the use of space by animals [16,17]. Videos from camera traps allowed us also to investigate the behaviour of wild animals using the food of guard dogs. Due to limits of population size, we decided to conduct a fuller analysis of the house sparrow, Passer domesticus, which has declined throughout Europe, partly due to lack of food, [18–21]. Additionally, we analyzed the influence of dog behaviour on the probability of house sparrow foraging. We predicted that aggressive behaviour of dogs would be treated by birds as a danger signal and would potentially negatively influence the probability of a visit [22]. Moreover, we expected that the response of birds to different dog behaviour, i.e., reaction or lack of reaction by feeding birds, would also be influenced by the sex of the bird [23]. 2. Material and Methods 2.1. Fieldwork The study was conducted in rural areas in western Poland, mainly in the vicinity of Pozna´n(52◦240 N, 16◦550 E). In total, 29 locations were selected where guard dogs were kept outside the property, and where owners regularly provided them with food and water. To avoid pseudo-replication, study locations were spaced apart by at least 1 km. Field work was carried out at the end of winter and early spring, i.e., at a critical period of availability of natural food sources for many farmland birds [6,9], from mid-February to the beginning of April 2016. At each location we set a Bushnell Camera Trap (NatureView HD Live View model No 119740), 1.5 m from, and aimed at, the dog food and water bowls. At each location the camera was installed for 24 h. Videos were initiated by a motion sensor and consisted of 30 s of movie with 1 s intervals [24]. The following parameters were collected at all locations: date, geographical coordinates, type of food fed to animals (purchased, home-prepared). Records were made of the type of bowl used by the observed animal (food bowl, water bowl), the place from where food was taken (bowl, food scattered), place of consumption (on the spot, taken away), and the species of the observed animal. In the case of house sparrows we determined the sex of the bird. We noted the dog’s reaction towards the animal taking its food if he ran to the bowl. We considered the dog reacted if it showed aggression more than once to animals taking food. Animals 2021, 11, 1198 3 of 8 2.2. Statistical Analysis We used a generalized linear mixed model (GLMM) with a negative binomial distri- bution to test the number of house sparrow visits compared to the type of supplementary resources, hereafter food type (home prepared food, purchased and water), sex (male or female), dog reaction (no-reaction, reaction). Additionally, we added the following inter- actions: food type × sex, food type × dog reaction and sex × dog reaction. We included location as a random factor. We used a least squares mean contrast with the Tukey method to compare between significant factor levels. For type of food, chi square contingency tests were used to compare the total numbers of visits between female and male house sparrow. All analyses were carried out in the R 3.3.2 statistical environment [25] using lme4 [26], lsmeans [27] and ggplot2 [28] packages.